1. The refinement of M603, a murine phosphocholine-binding antibody, has been continued at 2.7 angstrom and is now nearly complete. 2. The structure of J539, a murine galactan-binding monoclonal antibody, has been refined at 2.7 angstrom resolution. The refinement is now nearly complete. 3. Crystals have been obtained for the Fabs of 2 monoclonal antibodies against lysozyme and for their complexes with lysozyme. In at least one case the crystals, although small, look very promising for a more complete X-ray diffraction investigation.